1. Field of the Invention
The present invention relates to an light emitting diode (LED) backlight unit and a liquid crystal display device having the same, and more particularly, to an LED backlight unit that clearly establishes a light guide plate fixing structure in a liquid crystal display using a light guide plate dividing method, and a liquid crystal display having the same.
2. Description of the Related Art
In general, a liquid crystal display (LCD) device displays a desired image on a screen by controlling the amount of transmitted light being supplied from a backlight unit by the use of a liquid crystal panel including a plurality of liquid crystal cells arranged in a matrix format and a plurality of control switches for switching video signals to be supplied to the respective liquid crystal cells.
As for the backlight unit, cold cathode fluorescent lamps (CCFL) or light emitting diodes (LEDs) may be used according to the kind of a light source being used. Recently, light emitting diodes (LEDs), which consume less power, have lower weight and lower luminance than CCFLs, have come to prominence.
Backlight units are categorized into edge type backlight units and direct type backlight units, according to the arrangement of light sources thereof. According to an edge type backlight unit, light sources are arranged along the edges of the backlight unit, and light supplied from the side is guided using light guide plates and is then directed perpendicularly toward the liquid crystal panel. According to a direct type backlight unit, light sources are arranged at the rear of the liquid crystal panel, and light is supplied to the liquid crystal panel without the use of light guide plates.
In the related art, a structure has been proposed in which a screen on which images are displayed is divided and separately driven in order to provide high-quality images to users, and light is selectively supplied from a backlight unit through a divided light guide plate structure.
When an edge type backlight unit and a direct type backlight unit are compared with each other in terms of separate driving, both of them use an LED light source more than CCFLs because of the above-described advantages. In addition, a direct type backlight unit using an LED light source inevitably requires a predetermined distance between a liquid crystal panel and a backlight light source used to generate white light. On the other hand, an edge type backlight unit does not necessarily require a predetermined distance therebetween. As a result, the edge type backlight unit can meet miniaturization requirements.
FIG. 1 is a partial perspective view illustrating a configuration of an edge type local dimming backlight unit according to the related art.
As shown in FIG. 1, the edge type local dimming backlight unit according to the related art includes a lower cover 10 serving as a lower frame, a plurality of light guide plates 20 located on the lower cover 10, a reflective plate (not shown) interposed between the lower cover 10 and the light guide plates 20, LED sources 30 each arranged on the sides of the light guide plates 20 to supply light, and an optical member (not shown) located above the light guide plates 20.
Here, each of the LED light sources 30 includes a circuit board 31 and LED packages 32. The circuit board 31 has conductive lines to which voltage can be applied from an external source. The LED packages 32 are mounted onto the circuit board 31 to thereby supply light in response to the voltage being supplied from the external source.
The circuit board 31 may be disposed perpendicularly to the lower cover 10 having side walls at the edges thereof or may be disposed perpendicularly to the bottom surface of the lower cover 10 between the light guide plates 20, so that light from the LED packages 32 is supplied to the light guide plates 20 arranged at the front surface thereof.
As described above, when the plurality of light guide plates are arranged on the bottom surface of the lower cover, an assembly structure thereof is not definitely provided. Since the light guide plates may move in the case of external shocks, the luminance of specific portions may decrease.